The purpose of this task is to get students thinking about the domain and range of a function representing a particular context. Often when a function is being used to model a context, the expression for the function has a larger domain and range than is reasonable for the context. Asking students to focus on a function for which there is no formula focuses attention on the context itself. Note that in many contexts, there are multiple plausible sets that one could choose for the domain (and/or the range), and the solution to the current task provides such an example.